OKDER ERYSIPHALES (PERISPORIALES OF MOST AUTHORS) 



321 



Family Trichothyriaceae. This family of 5 or more genera and 20 

 or so species has been tossed about by mycologists since its members were 

 first studied. Mostly these forms have been assigned to the Erysiphales 

 or to the Hemisphaeriales, close to the Microthyriaceae. They are tropical, 

 parasitic on the epiphyllous mycelium of Meliola and on other fungi. It 

 was demonstrated by von Hohnel (1917) that the perithecia at maturity 

 lie inversely, with the original point of attachment outermost and the 

 asci radiating downward and outward from this point toward the onto- 

 genetically upper side. The perithecium arises terminally on a stout up- 

 right hypha which curves over as the development progresses. Eventually 



Fig. 103. Erysiphales, Family Atichiaceae. Atichia millardeti Racib. (= Seuratia 

 coffeicola Pat.). (A) Thallus when wet, showing ascigerous cushions. (B) Section 

 through portion of an ascigerous cushion. (C) Propagula. (A-B, courtesy, Arnaud: 

 Ann. sci. nat. Botan., 7:643-723. C, courtesy, Mangin and Patouillard, Compt. rend., 

 154(23) :1475-1481.) 



